1. Field of the Invention
The present invention relates generally to a vehicle cornering lamp system for changing the radiation angle of a lighting means when travelling on a curved road, and more particularly, to a cornering lamp for use in passenger automobiles.
2. Related Background Art
A vehicle, for example a car, has headlamps in its front right and left sides in order to radiate light forward when necessary (for example, at night). These headlamps fixedly radiate only the area in front of the car. Accordingly, the headlamps cannot radiate light in the direction the car is travelling when the car approaches a curved road. That is, in cornering, such as when turning around a curve, the headlamps cannot direct enough light in the travelling direction in which the car will go, causing drivers to fear the occurrence of a dangerous situation.
In order to improve such a problem, recently, a cornering lamp system (steering interlocking lamp system) has been proposed, which is designed to change the radiation direction (radiation angle) of headlamps correspondingly to the rotation angle of a steering wheel or the driving angle of front wheels, to radiate light in the travelling direction.
However, according to such a steering interlocking lamp system, when changing the radiation angle of headlamps in accordance with the rotation angle of a steering wheel, there is a problem that the correspondence between the rotation angle of the steering wheel and the radiation angle of the headlamps must be varied in accordance with the type of vehicle, since the gear ratio of a steering wheel varies in accordance with the type of vehicle involved. In addition, in the case where the radiation angle of the headlamps is varied in accordance with the driving angle of the front wheels, there is a problem in that the correspondence between the driving angle of front wheels and the radiation angle of the headlamps must be changed in accordance with the type of vehicle, since a wheel base also varies in accordance with the type of vehicle.
Therefore, the present inventors recently proposed a vehicle cornering lamp system in Japanese Patent Unexamined Publication No. Hei-5-80274. According to that cornering lamp system, the target position of a radiation angle of headlamps is obtained based on the vehicle speed and the rotational angular velocity (or the transverse acceleration). The current position of the radiation angle is controlled to coincide with the obtained target position. Accordingly, there is an advantage that the same structure of the system can be applied to any type of vehicle without adjusting the correspondence to the radiation angle.
However, in the aforementioned vehicle cornering lamp system proposed by the inventors in Hei-5-80274, it was determined during experimental testing that the radiation angle could not be changed quickly enough to adequately follow the rapid return of driver's eyes to a straight road when the vehicle exited a curved road.